The present invention relates to a new and improved construction of connection apparatus for a fire alarm containing a socket portion or socket member intended to be secured in the space or area to be monitored and a fire alarm portion or insert connectible with the socket portion by means of electrical and mechanical connection elements.
The heretofore known fire alarms, constructed as ionization fire alarms, optical fire alarms or as heat sensitive fire alarms or the like, as a general rule comprise a socket portion mounted at the ceiling or wall of the room or the like which is to be monitored and a fire alarm insert which can be mounted at the socket portion. This fire alarm insert is either connected by means of fixed clamps or with the aid of a contact system in a pluggable fashion with the socket portion. Different constructional embodiments of such prior art fire alarms, particularly their connection devices, have been shown in FIGS. 1, 2 and 3 of the accompanying drawings, and equally, in Swiss Pat. No. 355,380 (corresponding to U.S. Pat. No. 2,963,600, Meili et al.), using a plug or pin connection in accordance with the principles of electronic tubes, in Swiss Patent No. 508,251 (corresponding to U.S. Pat. No. 3,767,917, Lampart et al.), utilizing a bayonet connection, in German Patent No. 2,539,655 (corresponding to GB-Pat. No. 1 518 056 GEBA), using a central bayonet connection, and German Petty Patent No. 78 23178.4, using a rotationally symmetrical plug connection.
These heretofore known fire alarms are afflicted with the drawback that the servicing or maintenance personnel are confronted with extremely great difficulties as far as the maintenance and care of the fire alarms is concerned, which sometimes are mounted at difficultly accessible places. With some constructions of the state-of-the-art fire alarms it is necessary for the servicing personnel to climb upon a ladder, in order to retrieve the fire alarm from the ceiling of the room to be monitored. With other designs of prior art fire alarms the fire alarm inserts are constructed such that they can so-to-speak be "picked-off" the ceiling of the room by means of a tool mounted at a long rod or the like. The insertion of new or reconstructed fire alarm inserts in the fire alarm socket is accomplished in the same manner. What is disadvantageous with this technique is that the fire alarms frequently do not possess the correct mechanical or also electrical connection contacts. In practical terms, this means that when an alarm should be reported there has been mounted a functionally inoperative fire alarm. The quality and reliability of the mechanical and electrical connection elements is of decisive importance.
All of the heretofore known connection systems could not operate completely satisfactorily. Although it was possible to improve upon individual drawbacks of existing constructions, nonetheless in doing so it was necessary to again accept other drawbacks. In particular, corrosion problems arose during the course of the service time of a fire alarm, which not only markedly impairs or endangers the electrical contact, but also the mechanical connection elements.
Frequently, the fire alarms are in service in the presence of extremely rough ambient conditions; they are exposed to corrosive vapors, high moisture, dust deposition or the like, by way of example. Also, frequent faulty functionality of the fire alarms arises due to mechanical damage of the contact springs by the service or maintenance personnel. The heretofore known fire alarms attempt to take into account this problem in that the movable part of the electrical contact system, such as the contact spring 1 of the arrangement of FIG. 1 is arranged in the socket portion 4 and the rigid part 2 of the electrical contact system is arranged in the fire alarm insert. There are also known to the art fire alarms wherein the arrangement of the movable part and the rigid part of the electrical contact system is reversed, or where both in the socket portion and also in the fire alarm insert there are used resilient parts of the electrical contact system. If the resilient part is located at the fire alarm insert 3, as shown for the prior art arrangements of FIGS. 2 and 3, then the fire alarm can be examined visually by the service personnel for corrosion damage. However, in this case there exists the danger that during the revision work the contact springs 1 will become bent, leading to impairment in the functionality of the fire alarm.
Therefore, there have been proposed fire alarms wherein the contact springs 1 are arranged in the socket portion 4 of the fire alarm. With this proposal as shown in FIG. 1 there is however the drawback that the socket member, during the servicing operation, is not as readily accessible as the fire alarm insert and that corrosion phenomenon at the fire alarm-socket member go unnoticed.